1. Field of the Invention
The invention relates to an apparatus for purifying water by electrolytic purification, wherein the electrode used to create the electrolytic reaction is easily replaceable.
2. Description of the Related Art
Electrolytic purification of water has been carried out for some time. The process involves the purification of water that is saline, i.e., that has some concentration of halide ion in it. For instance, in many swimming pools in Australia, where electrolytic purification of pool water is currently more popular than in the United States, a slight salinity level is achieved by dissolution of quantities of sodium chloride into the pool water. The water, with its dissolved halide ion, is passed through an electrolytic cell. The halide ions are oxidized by electrolysis to form hypohalic acid, hypohalite ions, or both (believed to occur through the intermediate of molecular halogen), which have known utility in disinfecting water (and whose use is typically known as “chlorinating” the water). In addition, the electrolysis reaction converts water into hydrogen and oxygen; some of the oxygen is converted further into ozone, which also has a disinfecting effect on the pool water.
Electrolytic purification is desirable because it is safe, effective, and for applications such as swimming pools, hot tubs, spas, etc., it eliminates much of the need for the pool owner or operator to handle chemicals and monitor water chemistry. The salinity levels necessary to achieve effective chlorination levels are typically well below the organoleptic thresholds in humans, and the primary chemical required to be handled by the operator is a simple alkali metal halide salt. In addition, operation of the electrolytic cell is comparatively easy, and requires little attention beyond ensuring the proper current and voltage levels are set, and maintaining the correct salinity levels in the water.
One of the disadvantages associated with electrolytic purification is the cost of the electrolytic cell, as well as the cost of replacement electrodes, which can corrode, become fouled with scale and the like or otherwise become inactivated over time. These costs are primarily driven by the size of the electrodes, which are typically constructed from titanium coated with platinum or ruthenium. Electrodes having a surface area sufficient to generate adequate chlorine levels represent a significant portion of the cost of installing and maintaining an electrolytic purification system. In addition, electrolytic cell life is limited due to the current density through the cell over time.
One approach to minimizing these issues is to combine electrolytic purification with other purification techniques, as described in U.S. Pat. No. 6,761,827. However, many pools and spas continue to use electrolytic purification as the sole or primary purification technique. For these systems, eventually the electrode will corrode to the point where replacement is desirable and necessary. There remains a need in the art for an electrolytic purification system wherein the electrode cartridge is easily replaceable, where replacement will not compromise the water-tight, pressure resistant nature of the system, and where good electrical connections are obtained with the replacement cartridge.